Arrangement for switching a high-voltage switch by optical energy

ABSTRACT

An arrangement for switching a high-voltage switch by optical energy is proposed. The high-voltage switch comprises a number of controllable semiconductor elements, which switch through when illuminated with light. The light energy is transmitted via a light guide or optical fiber rod, and the angle between the light guide or optical fiber rod and the high-voltage switch is from 5° to 20°, and the light guide or optical fiber rod is cut obliquely on its end toward the high-voltage switch, producing an elliptical cross section.

BACKGROUND OF THE INVNETION

The invention is based on an arrangement for switching a high-voltageswitch by means of optical energy. From European Patent Disclosure EP 0377 619, A high-voltage switch is already known that takes over thefunction of an ignition voltage distributor when the high-voltagedistribution is in repose. This high-voltage switch is disposed betweenthe high-voltage-side output of the ignition coil and the spark plug,and it comprises semiconductor elements that have light-sensitive zones.The light-sensitive zones may be triggered by light-emitting elements insuch a way that they switch through at a predetermined time, forinstance corresponding to the ignition sequence. In the knownarrangement, fiber-optical light guides or light-emitting diodes aredisposed facing the light-sensitive zones of the high-voltage switch.Such an arrangement requires a relatively large amount of space wheninstalled in an ignition system. From German Patent DE 41 39 823, anarrangement of the light-emitting to light-sensitive element is known inwhich the light-emitting element is a light-emitting diode, and thelight-transmitting element comprises a number of photoconductive glassfibers melted together. The cross sections of the light inlet face andthe light exit face of the optical fiber rod are adapted here to theform of the facing light-emitting and the light-sensitive optoelectronicelement, respectively. To that end, the light exit face of thelight-transmitting optical fiber rod is reshaped from the originallyround cross section of the light inlet face facing the light-emittingdiode to a linear narrow cross section facing the rodlike optoelectronicsemiconductor switch. For deforming the cross section, the optical fiberrod is heated, shaped, and then in its new shape cooled down again. Inother words, a plurality of work steps are necessary.

SUMMARY OF THE INVENTION

The arrangement according to the invention has the advantage over theprior art that by obliquely bringing the light-transmitting element tothe longitudinal extension of the semiconductor switch, space-savingmounting of the semiconductor switch and the light-transmitting elementis possible.

It is especially advantageous that by the use of a rodlike fiber-opticallight guide or optical fiber rod as the light-transmitting element, theangle between the longitudinal axis of the light-transmitting elementand the longitudinal axis of the high-voltage switch can be chosen to bevery small. The beveling of the light-transmitting element on the sidetoward the high-voltage switch, so that an elliptical cross-sectionalface is created, has the advantage that the light-transmitting elementrests flatly against the circumferential face of the high-voltageswitch, and as a result the light energy can be carried very preciselyto predeterminable regions of the high-voltage switch. As a result, inthe final analysis, no additional work steps are needed to adapt thecross section of the light-transmitting element to the shape of thehigh-voltage switch. Because of the integration of the high-voltageswitch and the light-transmitting element in the spark plug connector,there is no need to additional mounting of the high-voltage switch withthe light-transmitting element on the cylinder head or ignition coil,for instance. The spark plug connector can thus be pre-mounted infinished form and then installed in its complete form, which makes forbetter handling since there is no need to mount still additionalindividual parts in the course of manufacturing an engine.

BRIEF DESCRIPTION OF THE DRAWING

An exemplary embodiment of the invention is shown in the drawing anddescribed in further detail in the ensuing description. The sole drawingfigure shows a spark plug connector in section, with the arrangementaccording to the invention of a high-voltage break-over diode andlighttransmitting element.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The drawing shows a spark plug connector 10, shown partly cutaway. Onone end, identified by reference numeral 11, this spark plug connector10 is connected to the highvoltage cable, not shown. The opposite end 12of the spark plug connector 10 has a cylindrical opening, which isslipped onto the spark plug, not shown. The internal structure of thespark plug connector is substantially equivalent to that of aconventional spark plug connector. The sole difference is the buildingin of the optoelectronic semiconductor switch 13 in the longitudinaldirection of the rotationally symmetrical longitudinal axis of the sparkplug connector. An interference-suppression resistor 14 is disposedbetween the terminal for the high-voltage cable 11 and theoptoelectronic semiconductor switch 13. The spark plug connector 10 hasa tubular housing 15. An opening 16 is provided in this tubular housing15, in the region of the optoelectronic semiconductor switch, throughwhich opening a light guide or optical fiber 17 is brought to theoptoelectronic semiconductor switch 13. The end of the optical fiber rodor optical fiber 17 contacting the optoelectronic semiconductor switchis cut off obliquely, so that the longitudinal axis of the optical fiberrod or optical fiber and the rotationally symmetrical longitudinal axisof the spark plug connector form an angle α of from 5° to 20°. Mountedon the end of the optical fiber rod or optical fiber 17 remote from theoptoelectronic semiconductor switch is a light-emitting diode, which isput in contact with a voltage supply, not shown, via a suitable plug.Reference numeral 19 represents the part toward the spark plug of theplug connection for contacting the light-emitting diode 18. The opticalfiber rod or optical fiber 17 is brought, with its obliquely cut,elliptical cross-sectional face, only to a portion of the optoelectronicsemiconductor switch 13. Thus only a portion of the optoelectronicsemiconductor switch is illuminated and switched through by means oflight energy.

The function of this spark plug connector is equivalent to the functionof an ignition voltage distributor. If the high-voltage switch is notlighted when the ignition voltage is applied, then the entire break-overdiode cascade blocks. If then the light-emitting diode 18 is triggeredin accordance with the ignition sequence, then the portion of theoptoelectronic high-voltage switch 13 to which the light energy iscarried is switched through, and the entire cascade fires, so that thehigh voltage is switched through to the spark plug.

This entire construction can be integrated with the spark plugconnector, so that only contacting of the light-emitting diode 18 thenneeds to be done once the spark plug connector has been built into theengine.

Naturally this integration is possible in spark plug connectors ofdifferent types as well. For instance, the spark plug connector may beT-shaped, in order to make the connection with the next spark plugconnector to it. At the same time, there are many possible ways toembody the connection of the light-emitting diode with the light guideor optical fiber.

We claim:
 1. An arrangement for switching an optoelectronic high-voltageswitch by means of optical energy, the arrangement comprisingsemiconductor means which at a predetermined voltage change abruptly toa conducting state; a light-emitting element; a light-transmittingelement which is disposed between said light-emitting element and theoptoelectronic high-voltage switch, said light-transmitting elementbeing arranged so that an angle formed by a longitudinal axis of thehigh-voltage switch and a longitudinal axis of said light-transmittingelement is between 5° and 20°.
 2. An arrangement as defined in claim 1,wherein said light-transmitting element is a light guide.
 3. Anarrangement as defined in claim 1, wherein said light-transmittingelement is an optical fiber rod.
 4. An arrangement as defined in claim1, wherein said light-transmitting element has a beveling on an end ofsaid light-transmitting element facing the optoelectronic high-voltageswitch, so that a resultant elliptical cross-sectional face of saidlight-transmitting element rests against a circumferential face of theoptoelectronic high-voltage switch.
 5. An arrangement as defined inclaim 1, and further comprising a spark-plug connector, theoptoelectronic high-voltage switch being integrated with said spark-plugconnector and arranged so that a longitudinal axis of the optoelectronichigh-voltage switch is located in a direction of a longitudinal axis ofsaid spark plug connector.
 6. An arrangement as defined in claim 1; andfurther comprising a spark plug connector, said light transmittingelement being integrated with said spark plug connector.